马铃薯根系分泌物及酚酸类物质对萎缩芽孢杆菌促生菌株QHZ3趋化成膜的介导作用

Effects of potato root exudates and phenolic acids on inducing chemotaxis of Bacillus atrophiae isolate QHZ3

摘要:

[背景] 根系分泌物介导的微生物趋化成膜是根际促生菌在根际定殖及功能发挥的重要前提，深入了解该过程对理解菌株定殖机制具有重要意义。[目的] 探明马铃薯根系分泌物中使萎缩芽孢杆菌促生菌株QHZ3在根际趋化成膜的信号物质。[方法] 通过高效液相色谱鉴定马铃薯根系分泌物中的主要酚酸类物质，采用半固体平板法与类毛细管法比较马铃薯根系分泌物和不同酚酸类物质对促生菌株QHZ3趋化作用，并通过结晶紫染色法观察马铃薯根系分泌物和不同酚酸类物质对菌株QHZ3生物膜形成的影响。[结果] 马铃薯根系分泌物中的酚酸类物质主要包括富马酸、对羟基苯甲酸、阿魏酸和肉桂酸。半固体平板法结果显示，马铃薯根系分泌物和4种酚酸对菌株QHZ3均具有趋化作用，富马酸的趋化作用最强；类毛细管定量试验结果表明，不同浓度酚酸对菌株QHZ3的趋化作用不同，中高等浓度的富马酸（25—100μmol/L）和低浓度的阿魏酸（10 μmol/L）对菌株QHZ3的趋化作用最强；结晶紫染色法结果表明，120—240 μg/ml马铃薯根系分泌物和50—75μmol/L富马酸及100 μmol/L对羟基苯甲酸可显著促进菌株QHZ3生物膜的形成，而阿魏酸和肉桂酸对菌株的生物膜形成没有显著影响。[结论] 根系分泌物和酚酸均可介导菌株QHZ3在马铃薯根际趋化成膜，但4种酚酸的作用不同，富马酸和阿魏酸对菌株的趋化作用显著，富马酸和对羟基苯甲酸则是对菌株生物膜的形成具有显著影响。

Abstract:

[Background] Chemotaxis of microorganisms mediated by root exudates is an important prerequisite for root colonization and function of plant growth-promoting rhizobacteria (PGPR), and further understanding of this process is of great significance to understand the colonization mechanism of the strains. [Objective] To study the signal substances in root exudates of potato which can promote the colonization of PGPR QHZ3 in rhizosphere. [Methods] The some phenolic acids in potato root exudates were identified by high performance liquid chromatography (HPLC). the chemotaxis of potato root exudates and different phenolic acids to isolate QHZ3 were compared using the semi-solid plate method and capillary-like method. the effects of different phenolic acids on biofilm formation of QHZ3 were observed by crystal violet staining. [Results] Phenolic acids in potato root exudates mainly included fumaric acid, p-hydroxybenzoic acid, ferulic acid and cinnamic acid. The semi-solid plate method shows that both the root exudates of potato and the four phenolic acids mentioned above had chemotactic effects on strain QHZ3, and the chemotactic effect of fumaric acid was the strongest. capillary-like quantitative test showed that the chemotactic effect of phenolic acids on strain QHZ3 was different at different concentrations. The chemotactic effect of middle and high concentrations of fumaric acid (25—100 μmol/L) and low concentration of ferulic acid (10 μmol/L) on strain QHZ3 was the strongest. Crystal violet staining showed that 120—240 μg/ml potato root exudates, 50—75 μmol/L fumaric acid and 100 μmol/L p-hydroxybenzoic acid could significantly promote biofilm formation of QHZ3, while ferulic acid and cinnamic acid had no significant effect on biofilm formation. [Conclusion] Both root exudates and phenolic acids could mediate the chemotaxis of strain QHZ3 to form biofilm in potato rhizosphere, but the effects of four phenolic acids were different. The chemotaxis of fumaric acid and ferulic acid was significant, while fumaric acid and p-hydroxybenzoic acid had significant effects on the formation of biofilm.